Aims

 当年生小枝是多年生植物体上最活跃的部分之一, 其生物量分配是植物生活史对策研究的一个重要内容。该文采用标准化主轴估计(Standardized major axis estimation, SMA)和系统独立比较分析(Phylogenetically independent contrast analysis, PIC)的方法, 研究了杜鹃花属(Rhododendron)植物一年生小枝的大小对小枝叶片、叶柄和茎的生物量分配的影响, 以及对叶面积支持效率(即单位质量小枝支持的叶面积)的影响。结果显示: 1)小枝大小对叶片生物量分配比率的影响不显著, SMA斜率为1.040 (95%的置信区间(CI)=0.998～1.085); 但是, 小枝越大, 叶柄生物量分配比例越高(SMA斜率为1.245, 显著大于1.0, 呈显著的异速生长关系)。2)小枝越小, 单叶面积越小(支持Corner法则), 单位质量小枝所支持的叶面积越大, 即具有较小枝条和较小叶片的物种可能具有较高的叶面积支持效率。这些结果有助于我们更好地理解亲缘关系十分接近的杜鹃花属植物, 在不同生境条件下叶片大小的差异, 以及为什么在胁迫生境条件下小叶物种更为常见。

EFFECTS OF TWIG SIZE ON BIOMASS ALLOCATION WITHIN TWIGS AND ON LAMINA AREA SUPPORTING EFFICIENCY IN RHODODENDRON: AL. LOMETRIC SCALING ANALYSES

Aims Current-year shoots (twigs) are the most active compartment in plants. Biomass allocation within twigs is an important parameter categorizing plant life history strategies. Our objective was to explain variation in leaf size among habitats and why small-leaved species are more likely to be seen in severe habitats than large-leaved species. Methods Effects of twig size on biomass allocation among lamina, stem, and petiole and on lamina supporting efficiency were estimated using standardized major axis estimation. Correlation between parameters was examined using the phylogenetically independent comparative method. Important findings Fractional lamina mass was found to be independent of twig size, but allometric relationships were found between stem mass and petiole mass and between lamina area and stem mass. Petiole mass increased disproportionally with stem mass, while lamina area failed to keep pace with the increase in stem mass. Species with smaller twigs and smaller leaves may be advantageous in lamina area supporting efficiency over their counterparts.